| 1. |
- Marklund, Mattias, 1970-, et al.
(författare)
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High intensity physics current and future possibilities
- 2009
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 1188:1, s. 301-314
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Tidskriftsartikel (refereegranskat)abstract
- The capability to produce high field strengths, and thereby obtain a new means for doing fundamental physics, has over the last thirty years taken great leaps forward. Both superconducting cavities as well ultra-intense lasers can now reach field strengths of the order 50 MV/m (stationary) and 1012 V/m (peak value, time-dependent field), respectively. Here we will describe a collection of problems that catches the flavor of the nonlinear quantum vacuum and the possibility to use high field strengths as a low-energy probe of fundamental physics.
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| 2. |
- Hebenstreit, Florian, et al.
(författare)
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Pair production : the view from the lightfront
- 2011
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Ingår i: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 84:12, s. 125022-
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Tidskriftsartikel (refereegranskat)abstract
- We give an exact, analytic, and manifestly gauge invariant account of pair production in combined longitudinal and transverse electromagnetic fields, both depending arbitrarily on lightfront time. The instantaneous, nonperturbative probability of pair creation is given explicitly along with the spectra of the final particle yield. Our results are relevant to high-intensity QED experiments now being planned for future optical and x-ray free electron lasers.
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| 3. |
- Hebenstreit, Florian, et al.
(författare)
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Strong field effects in laser pulses : the Wigner formalism
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 83:6
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Tidskriftsartikel (refereegranskat)abstract
- We investigate strong field vacuum effects using a phase space approach based on the Wigner formalism. We calculate the Wigner function in a strong null-field background exactly, using lightfront field theory. The Wigner function exhibits the distinct features of strong field QED: in particular we identify the effective mass in a laser pulse, compare it to the well-known mass shift in a periodic plane wave and identify signals of multi-photon absorption and emission. Finally, we show how to extend our results to descibe vacuum pair production in colliding laser pulses.
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| 4. |
- Heinzl, Thomas, et al.
(författare)
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Finite size effects in stimulated laser pair production
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 692:4, s. 250-256
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Tidskriftsartikel (refereegranskat)abstract
- We consider stimulated pair production employing strong-field QED in a high-intensity laser background. In an infinite plane wave, we show that light-cone quasi-momentum can only be transferred to the created pair as a multiple of the laser frequency, i.e. by a higher harmonic. This translates into discrete resonance conditions providing the support of the pair creation probability which becomes a delta-comb. These findings corroborate the usual interpretation of multi-photon production of pairs with an effective mass. In a pulse, the momentum transfer is continuous, leading to broadening of the resonances and subthreshold behaviour. The peaks remain visible as long as the number of cycles per pulse exceeds unity. The resonance patterns in pulses are analogous to those of a diffraction process based on interference of the produced pairs. We finally comment on the dependence of the peak positions, and in turn the effective mass, on the pulse shape.
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| 5. |
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| 6. |
- Ilderton, Anton, 1978-, et al.
(författare)
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Infra-red problems and a response
- 2009
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Ingår i: QCD-TNT09. ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- The standard approach to the infra-red problem is to sum over degenerate final states to remove soft divergences (Bloch-Nordsiech), and over both initial and final states for collinear divergences (Lee-Nauenberg). We show that this division is inconsistent, and further that the Lee-Nauenberg recipe leads to ill-defined results in a variety of theories. We then argue that infra-red divergences are due to using unphysical variables to describe in and out states and introduce gauge invariant, physical ‘dressed’ states. Perturbative and non-perturbative properties of physical electron and quark states are then discussed. It is shown in SU(2) lattice simulations that the overlap between the ground state and our dressed state increases as we approach finer lattices.
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| 7. |
- Ilderton, Anton, 1978-
(författare)
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QED processes in intense laser fields
- 2012
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Ingår i: International Journal of Modern Physics: Conference Series. - : World Scientific. - 2010-1945. ; 14, s. 394-402
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Ilderton, Anton, 1978-, et al.
(författare)
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Symmetry breaking, conformal geometry and gauge invariance
- 2010
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Ingår i: Journal of Physics A. - : IOP Publishing. - 0305-4470 .- 1361-6447. ; 43:31, s. 312002-
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Tidskriftsartikel (refereegranskat)abstract
- When the electroweak action is rewritten in terms of SU(2) gauge-invariant variables, the Higgs can be interpreted as a conformal metric factor. We show that asymptotic flatness of the metric is required to avoid a Gribov problem: without it, the new variables fail to be nonperturbatively gauge invariant. We also clarify the relations between this approach and unitary gauge fixing, and the existence of similar transformations in other gauge theories.
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| 9. |
- Ilderton, Anton, 1978-
(författare)
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Trident pair production in strong laser pulses
- 2011
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Ingår i: Physical Review Letters. - : The American Physical Society. - 0031-9007 .- 1079-7114. ; 106:2, s. 020404-
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Tidskriftsartikel (refereegranskat)abstract
- We calculate the trident pair production amplitude in a strong laser background.We allow for finite pulsedurations, while still treating the laser fields nonperturbatively in strong-field QED. Our approach revealsexplicitly the individual contributions of the one-step and two-step processes.We also expose the role gaugeinvariance plays in the amplitudes and discuss the relation between our results and the optical theorem.
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